Known laboratory ventilating systems such as disclosed in WO2007033821A1 generally comprise an intrinsically stiff carrier frame mounted on the ceiling of the laboratory to which the air supply conduits and exhaust air conduits are then attached above the walking area of the laboratory. Although these known ventilation arrangements have a high degree of flexibility with respect to expandability and changes in the spatial conditions of the laboratory, they are comparatively expensive and complex to install and mount due to their large size, and intrinsically stiff carrier frame. Moreover, they lower ceiling or overhead height in the walking area.